This invention relates generally to a wristwatch with hands and calendar date ring driven by the watch motor. More particularly, it relates to an improved mechanism for manually changing the date without interfering with the normal timekeeping or date advancing functions of the watch.
Calendar watches are well known in the art which, in addition to normal time indicating hands, include a circumferential ring of numbers showing the calendar date. Such watches usually require manual adjustment of the displayed date for months having fewer than 31 days. Illustrative of the prior art are the following patents which are exemplary, but not intended to be all inclusive:
______________________________________ Pat. No. Issue Date Patentee ______________________________________ 3,413,800 12/3/68 G. Dubois et al. 3,645,086 2/29/72 E. Niznik 3,716,983 2/20/73 Tanaka et al. 4,291,397 9/22/81 Wuthrich et al. ______________________________________
Such calendar watches, which include means to manually change the date indication, normally include an external actuator which may be operated to advance the date. Usually the date may be manually advanced, but not retarded or moved in the opposite direction.
One of the common problems with such systems is that, if there is an attempt to manually advance the date at the precise time when the normal timekeeping mechanism is also advancing the date, damage can result to the delicate internal mechanism of the watch. One effort to avoid such damage is illustrated in German Offenlegungschrift DE No. 3046569A1 in the names of Schwartz and Skwarek, laid open on July 15, 1982, and assigned to the present assignee.
The present invention incorporates a planetary gear. Planetary or epicyclic gears have previously been suggested in watches, for example in gearing driving the hands for normal timekeeping, as in U.S. Pat. No. 3,722,207 issued Mar. 27, 1973 to Challandes; U.S. Pat. No. 3,184,909 issued May 25, 1965 to Lohf et al.; and U.S. Pat. No. 4,254,493 issued Mar. 3, 1981 to A. Billet, the latter assigned to the present assignee. Planetary gears have also been suggested for the winding mechanism of mechanical watches by P. Wuthrich in U.S. Pat. No. 3,104,517 issued Sept. 24, 1963, assigned to the present assignee.
The advent of the quartz analog stepping motor watch has imposed more severe requirements upon the drive mechanism which advances the calendar date ring. Since the power to drive the ring is derived from a tiny stepping motor driven by electronic pulses from an integrated circuit, rather than from a spring motor, a drive mechanism which conserves battery life is essential. Also, there is an ever increasing tendency toward thinner and thinner watches, which nevertheless must continue to employ economic construction, simplicity of assembly, and fewer parts. Plastic materials for gear members offer many advantages in cost and in the ability to produce complex shapes.
Accordingly, one object of the present invention is to provide an improved calendar watch with means to adjust the date indication without disturbing the normal function of the watch or causing damage.
Another object of the invention is to provide an improved quartz analog stepping motor calendar watch which is thin and incorporates a manually adjustable calendar drive mechanism of low cost plastic parts.
Another object of the invention is to provide an improved calendar watch with a planetary gear mechanism for changing the date indication in either direction from outside the watch without damage.